In view of structure, a cabin of heavy equipment should be designed such that an operator works comfortably. Moreover, in view of structure, the operator should be protected from such an unexpected accident that a heavy object falls toward the cabin during the driving or the heavy equipment is overturned at a sloped terrain during the work.
Recently, it is urgently required to develop a technology of cabin protective structure capable of securing the safety of operator on the spot as organizations such as the International Standardization Organization (ISO), the Society of Automatic Engineers (SAE) or the like become to reinforce the regulation for the cabin protective structure more strictly.
The EOPS (Excavator Operator's Protective Structure) should be designed to substantially support a load applied to a cabin in lateral, backward and vertical directions so that a transformed cabin or a heavy object does not damage an operator's body when a heavy object impacts a cabin in a lateral, vertical or backward direction during a running operation of heavy equipment.
FIG. 1 is a cross sectional view illustrating a conventional load support apparatus for a cabin of heavy equipment.
A cabin 10 is mounted on upper frame 20 using various fixing members, with the upper frame 20 being rotatably fixed to a lower driving body (not shown). If the cabin 10 is directly mounted on the upper frame 20 by a certain fixing member such as bolts, etc., the impact of the upper frame 20 may be directly applied to the cabin 10. Working conditions of heavy equipment are generally bad. Since the vibrations or noises occurring at the upper frame 20 are directly applied to the cabin 10, an operator may feel fatigue quickly.
So as to reduce the above vibrations, a plurality of vibration absorption apparatuses 40 and 40′ are installed at the front and rear sides of the cabin 10, with the vibration absorption apparatuses 40 and 40′ being designed to absorb the upward and downward vibrations of the cabin 10 between the upper frame 20 and a bottom plate 30 of the cabin 10, with the upper frame 20 including a plurality of through holes 18 at the upper surface of the same. The vibration absorption apparatuses 40 and 40′ are engaged with the upper frame 20 by the through hole 18 and bolt members (not shown) with the flange 42 being engaged with the upper surface of the upper frame 20.
The vibration absorption apparatuses 40 and 40′ have elastic members such as coil springs, rubber or elastic liquid material therein, and the cabin 10 is mounted on the upper frame 20 with the flange 42 and the bolt member. With the above constructions, the operator feels less fatigue based on a damping effect to the up and down movements and external impacts due to non-uniform ground surface.
As described above, the vibration absorption apparatuses 40 and 40′ well absorb the up and down movements occurring by external impacts due to non-uniform ground surface. However, the left and right movements cannot be well absorbed thereby. As a result, cracks may occur by left and right movements or forward or backward movements at the fixed portions of the vibration absorption apparatuses 40 and 40′.
Therefore, the vibration displacement due to left and right movement increases, cracks may occur at the fixed portions of the vibration absorption apparatuses 40 and 40′ engaged with the cabin 10. Namely, the cracks may occur at the flanges 42 and the bolt member for thereby increasing safety accidents.
When the loads applied in the front or side direction of the cabin 10 is sequentially transferred to the cabin 10, the bottom plate 30, the vibration absorption apparatuses 40 and 40′ and the upper frame 20, the vibration absorption apparatuses 40 and 40′ absorb part of the up and down vibrations, while supporting the weight of the cabin. However, the vibration absorption apparatuses do not have enough strength with respect to a considerable impact exceeding the elastic limit of the vibration absorption apparatuses 40 and 40′. In particular, in the case of an emergency situation such as an overturn accident, the cabin 10 may be escaped from the upper frame 20 due to an external impact, so that the cabin cannot be safely protected from external impacts.